The present invention relates to a bar-type dental attachment that can be used to fix a denture by a magnetic attractive force to the jawbone via dental implants.
As shown in FIG. 3 and FIG. 4, in dental treatment there currently exists a bar and clip type dental attachment used to fix a denture to an implant. In this type of attachment, the denture is clipped to a cylindrically shaped bar 41, which is supported by a fixed base embedded in the jawbone, with clips 42 implanted in the denture base. In this attachment, clips fix the denture elastically.
But using this clip and bar type dental attachment, one must press the clips made of mental or plastic on to the bar when putting in the denture and denture is not easily inserted. Furthermore, there is a problem of wear between the clips and the bar.
On the other hand, as is shown in laid-open Japanese patent number 8-317941, there are have been many attempts to use magnetic attractive force to fix a denture to implants because dentures are easily inserted and removed when fixed via magnets.
But these prior attachments using magnetic attractive force are abutment type attachments, which differ from bar type attachment. Furthermore, in these prior attachments, the attractive face between the magnetic assembly embedded in the denture base and the keeper embedded in the abutment is a flat surface. So, the prior attachments using magnetic force cannot revolve according to the movement of the denture during occlusion because said attractive face is a flat surface. And the magnetic assembly embedded in denture base cannot be used with this bar type keeper because the contact face of said bar type keeper has a cylindrically shaped lateral face and the two pieces will not fit.
Considering these problems, the present invention offers a bar type dental attachment for implants, which can revolve according to the movement of the denture during occlusion, is easy to insert and remove, and is highly resistant to wear.
The present invention of a bar type dental attachment for use with implants comprises a bar shaped keeper which is supported by a fixed base embedded in the jawbone and has at least one section that is an arced attractive surface whose radius of curvature is fixed, and a magnetic assembly comprising: a magnetic body whose magnetic polls face the yoke plates; a pair of yokes which is arranged on both sides of said magnetic body in a sandwich-like fashion, each of which has an attractive face opposite to said attractive face of said keeper, and which fit easily to said attractive face of said keeper; a seal part made of anticorrosive non-magnetic material which hermetically seals at least a part of the lateral face of said magnetic body between said pair of said yoke plates.
The present invention of a bar type dental attachment for implants makes it easy to insert or remove a denture because the denture is fixed to the implants by magnetic attractive force. That is, it is different from prior attachments, which fix dentures elastically by using clips, because it is unnecessary to insert the denture precisely or to press the denture in, and it is possible to insert or remove the denture with a simple motion.
Because the pair of yoke plates of the magnetic assembly of presently invented dental attachment has an attractive face whose shape fits to the arc shaped section of the bar type keeper, the magnetic assembly fits to the keeper well. The present invention also has single-axis rotation and can move corresponding with the seesaw movement of the denture during occlusion. In addition, because the pair of said yoke plates is arranged on both sides of the magnetic body like a sandwich and the magnetic circuit is closed, the magnetic attractive force between the keeper and the magnetic assembly is strong, so the present attachment can sufficiently retain denture.
Because the seal part made of anticorrosive non-magnetic material hermetically seals at least a part of the lateral face of the magnetic body between the pair of yoke plates, and because the entire circumference of the magnetic body is completely enclosed by said yoke plates and seal part, the magnetic body is not corrosive even though a magnet itself is relatively easy to corrode inside the oral cavity.
This seal part, being welded hermetically between a pair of yoke plates, can be a ring-shaped cap that covers the lateral face of the magnetic body. The structure, in which a ring-shaped cap covers the lateral face of a magnetic body and the pair of yoke plates is exposed, enables magnetic body, as is mentioned above, to avoid corrosion while the entire volume of the magnetic assembly is kept small. Therefore, the dental attachment becomes a more suitable size to be used in the mouth.
Furthermore, the magnetic assembly of the present bar type dental attachment for implants can have a convex, or a concave part on the lateral face opposite to said attractive face. With such a concave or convex part, the magnetic assembly can be fixed more firmly to the denture base. Even though the magnetic assembly is embedded in a dental base with adhesive resin, after long use, separation from denture base may occur. By forming said convex or concave part, the magnetic assembly is fixed under a condition wherein said concave part digs into the denture base, or said concave is filled with the denture base. Therefore separation of the magnetic assembly and denture base can be more surely prevented.
The present invention of a bar type dental attachment for implants can have a primer coat on the surface of the magnetic assembly except for the attractive face. The primer coat has a function similar to that of said convex or concave part, in that the magnetic assembly is more firmly fixed with resin material of denture base.
And preset invented bar type dental attachment for implants can have a surface treatment on said attractive face to enhance the resistance to wear. By giving a surface treatment to the attractive surface in contact with a keeper, wear on the attractive face of the magnetic assembly during occlusion or over repeated insertion and removal can be diminished and the dental attachment can have a longer life.
These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings.